Equation-of-State Analysis of Binary Copolymer Systems. 2. Homopolymer and Copolymer Mixtures

Abstract

The perturbed hard-sphere-chain (PHSC) equation of state for copolymer systems is applied to binary homopolymer blends and to mixtures of homopolymer and copolymer. Theoretical results for the effect of copolymer composition on lower critical solution temperature (LCST) are compared with experiment for homopolymer/copolymer mixtures containing poly(methyyl methacrylate-co-styrene) (MMAco-S) and poly(acrylonitrile-co-styrene) (AN-co-S) random copolymers. The intersegmental parameters for the MMA-S and AN-S pairs are obtained from the miscibility maps containing MMA-co-S and ANco-S random copolymers, respectively, differing in copolymer compositions. The homopolymer/copolymer systems studied in this work exhibit LCSTs in the experimentally accessible temperature range as the copolymer approaches 100% polystyrene. The PHSC equation of state predicts that the LCST of a homopolymer/copolymer system exhibits a maximum as the copolymer composition varies. Unique values are assigned to the intersegmental parameters for a given pair of segments.

Investigation of Blend Miscibility of a Ternary PS/PCHMA/PMMA System Using SIMS and Mean-Field Theory

“…This type of phase behavior can often be attributed to specific interactions, such as hydrogen bonding, 16 or large differences in polymer free-volume. 17 Previously investigated binary LCST blends have included polystyrene (PS) in combination with poly-(xylenyl ether) (PXE), 1,14 poly(vinyl methyl ether) (PVME), 7,18 or tetramethylbisphenol A polycarbonate (TMPC). 12,13 Although these systems have been employed for investigations of such phenomena as surface segregation 7 and mutual or self-diffusion, 1,12-14 they suffer from highly asymmetric glass transition temperatures (T g 's).…”

“…Miscible polymer blends have been model systems for investigation of polymer dynamics − and equilibrium segregation at polymer surfaces − and polymer/polymer interfaces. , They are often composed of polymer pairs that have an apparent exothermic enthalpy of mixing. ,,− Characterized by a lower critical solution temperature (LCST) type phase behavior, these systems are miscible at low temperatures when χ AB < 0, where χ AB is the mean-field enthalpic interaction parameter between homopolymers A and B, and tend to phase separate as they are heated above the critical temperature ( T c ). This type of phase behavior can often be attributed to specific interactions, such as hydrogen bonding, or large differences in polymer free-volume , poly(vinyl methyl ether) (PVME), , or tetramethylbisphenol A polycarbonate (TMPC). , Although these systems have been employed for investigations of such phenomena as surface segregation 7 and mutual or self-diffusion, ,− they suffer from highly asymmetric glass transition temperatures ( T g 's).…”

Dependence of solvent quality on the composition of copolymers: experiment and theory for solutions of P(MMA-ran-t-BMA) in toluene and in chloroform

“…Some of them report experimental data and their theoretical interpretation, [4][5][6] others deal preferentially with the modeling. [7][8][9][10][11][12][13] We have undertaken the present study to broaden the general knowledge concerning the thermodynamic solution behavior of random copolymers and to test a unied thermodynamic approach, 14 which is according to the present experience generally applicable, independent of the molecular and chemical architecture of the components and of other dissimilarities, like electrical charges. Here we wanted to check the universality of this concept by applying it to solutions of random copolymers.…”

Modeling Comblike Polymer Solutions Using an Equation of State: Application to Vapor−Liquid Equilibria

“…Moreover, the GFD theory has been extended to hard heteronuclear chain fluids and heteronuclear tangent square-well chain fluids has been applied to estimate vapor−liquid equilibria (VLE) and liquid−liquid equilibria (LLE) , for copolymer solutions.…”